Method of making fills and inlays in wood



Patented 0a. 20, 1936 METHOD OF MAKING FILLS AND TNLAYS IN WOOD Clyde A..Crowley, Chicago, 11!.

No Drawing.

Application November 10, 1933; Serial No. 697,529

3 Claims. (01. 106-22) This invention relates to a new method of fill: ing apertures or crevices in wood, either for the P p se of repair or for the purpose of ornamentally decorating the wood. Though the problem of forming fills or inlays in wood might seem fairly easily solved, upon superficial consideration, still the fact remains that there is not in existence at this time a method of constituting fills or inlays in wood which is truly satisfactory or used as-anythlng but a make-shift. I

It has been common practice in the past to use putty, lead mixtures and the like, then paint over these, but the difiiculty has been that these materials did not harden properly and were too different in nature, composition and hardness from the wood to be useful over any substantial range of situations. It has likewise been proposed to constitute the fills or inlays with a plastic material comprising a resin, solvent and filler. While this type of composition permitted the character of the wood to be more closely approximated than previous methods, still it had the inherent disadvantage that evaporation of the solvent brought about shrinking of the plastic mass so that the fill or inlay became loose as it dried and did not adhere in place properly.

Obviously, if an aperture in a piece of wood is filled with a plastic material containing a solvent which evaporates, the fill must lose either volume or density. An object of the present invention is to provide a fill or inlay which loses density rather than volume. Any method of constituting fills or inlays, however, to be fully satisfactory, must do far more than simply fill up an aperture. Even if there were no shrinkage or loss of volume, the fill or inlay would be rather loose and subject to displacement under slight stress. The material constituting the fill or inlay should therefore be adhesively contacted with the walls of the aperture or crevice and should be of such a nature as to wet and adhere to the walls. Moreover, it is within the contemplation of this invention that the forming of fills or inlays may be utilized to hold metal'parts in vibrationless con- "tact with wood '50 it is likewise desirable that the material constituting the fill or inlay have the capacity of wetting and adhering to metal. The satisfactory method of constituting fills or inlays likewise requires that the hardness or flexibility of the inlay may be varied to correspond to the hardness or the flexibility of the wood so that the two may be tooled, that is, sawed, planed or otherwise worked as a unitary body.

If the inlay be for ornamental purposes, it is desirablethat pigments or coloring substances be incorporable in it. If, however, the fill is for repair purposes it is desirable that the fill be able to absorb either spirit stains or oil stains substantially to the extent the surroundingwood does and likewise that paints and lacquers adhere to the fill substantially as well as to the surrounding WoOd.

'It is the general object of this invention to provide a method of forming fills or inlays which provides the novel utilities specified above. Broadly speaking, the method of this invention 5 comprises pressing into adhesive contact with the walls of a wooden crevice or aperture, a plastic composition comprising a vinyl resin, a solvent therefor, and a cellulosic material, then permitting the solvent to dry out. The admixture of these materials provides a fill which dries solidly, which does not pull away from the edges of the aperture or crevice, with which it is in adhesive contact, upon drying, and which loses density rather than. volume so that it fills the aperture or crevice.

It is likewise believed that it is this loss of density which renders the fill or inlay substantially like the surrounding wood from the point of view of the absorption of stains or the adhesion .of paints or lacquers. Otherwise expressed, it is believed that the adhesion of the plastic to the walls of the aperture or crevice and the loss of density rather than volume upon evaporation of the solvent, produces virtually a new composition 25 of matter behaving in respect to stains, paints and lacquers more like wood itself than like the ordinary resins of the vinyl type.

After drying, the fills or inlays made according to this invention are depressed very slightly toward their centers. Likewise. the immediate outer surface of the fills or inlays are not particularly absorbent in relation to wood stains. It is therefore recommended in practicing this invention, particularly where wood stains are to be 35 used, that the piece of wood including the fills be planed or scraped to provide a completely level surface and likewise to remove the very outer layer of the fill, thereby exposing the more Porous interior. The piece of wood with the fills may then be finished by staining, painting or lacquering, just as if it were a unitary, homogeneous structure.

While a rather wide variety of ingredients can be used in the fills or inlaysof the nature described according to the precise qualities desired in the fill or inlay, the three dominant components of the inlay are the vinyl resin, the solvent therefor, and the cellulosic material.

The invention is not restricted to the use of any particular vinyl resins. I have found that satisfactory resins are those formed by the poly-. merization of two or more vinyl compounds while in mutual contact, that is, by conjoint polymerization, and that a preferred type of resin is that resulting from the conjoint polymerization of 70% or more by weight of vinyl chloride and 30% or toluene. Resins of this type may be formed by polymerizing the above stated proportions of vinyl chloride and vinyl acetate in the presence of a catalyst, suchas benzoyl peroxide, and a liquid medium, such as'parafiin hydrocarbons, aliphatic alcohols, ketones, and the like, at a temperature below about 60 C. This resin may be dissolved in a suitable solvent such as acetone, the strength or the solution being, for instance, 2.25 parts by weight of the resin to approximately 10 partsby weight of acetone.

Other well known solvents for the vinyl resin "may be used if desired, such as methyl acetone or other solvent mixtures consisting of ketones, a1- cohols, esters, including the glycol esters, or aromatic hydrocarbons. However, the use of acetone or a dominating quantity of acetone is particularly recommended for the reason that it evaw rates very readily, and moreover, its use seems to contribute to the porosity of the resulting product. Otherwise expressed, the use of acetone seems to contribute to the desired result, namely, that in drying, the filler inlay loses density to a marked extent and loses volume only to a very minor extent.

The cellulosic material may be sawdust or wood flour, of either hard wood or soft wood, of any mesh desired. v However, a soft wood flour so fine as to pass through a one-hundred mesh sieve, has

been found to be highly suitable for a plastic material of the type described.

Various modifying resins, fillers orplasticizers may be used. Other fillers may be used such as powdered asbestos, chalk, silica, diatomaceous earth, slate flour, powdered mica, or coloring pigment. Supplement resinous materials or gums may be used, such as colophony or ester gum. For the purpose of making the filler or inlay more flexible, plasticizers may be employed, such as dibutyl phthalate, tri-cresyl phosphate, dibutyl cellosolve phthalate, camphor, water insoluble oleates and stearates, high boiling point ketones. Generally speaking, the plastic compositions adapted for use in the practice of this invention have substantially the following composition:

(A) A binding solution consisting of Per cent by weight 1. Avinyl resin -....from 25 to 8 2. Aresinous substance do 0 to 25 3. Asolvent mixture do to 57 4.- A plasticizing substance do.. 0 to 10 vinyl resin solution (25% resin 75%- acetone by weight) I r I 28 Ester gum solution (50% gum 50% acetone by weight) 24 mesh wood flour 18 Vinyl resi Ester gum Wood flour Aceton The plasticmaterlal suitable for practicing this invention preferably is a very viscous mass which does not run or fiow easily, which is plastic under pressure, and which is very tacky and adhesive.

In practicing this invention the aperture or crevice in the piece of wood is first cleaned to remove all particles of 'foreign'matter. Then the plastic material is pressed into the aperture or crevice or forced in under pressure so that it wets the walls of the aperture or crevice. The adhesion is of course greater if the walls in question are rough rather than smooth. Likewise, if it is desired to put a metal insert of any sort in the mass of plastic material in the aperture or crevice, it is recommended that the walls of the metal beroughened to permit greater adhesion of the.

plastic material. I

The aperture or inlay so constituted is then permitted to dry. It is recommended that the drying be slow in'order to avoid drying the outside of the plastic mass first and thereby tending to seal the solvent in the interior of the plastic mass.

However, as pointed out before, the plastic in question tends to lose density rather than volume and the loss of density tends to facilitate the complete escape of the solvent.

wood, yield to the working tools to 'substantially the same extent as the surrounding wood, and take stains, paints and lacquers to substantially the same extent as the surrounding wood. Obviously, by choosing the cellulosic filler correctLv in respect to the wood in which the fill is made, I

the correspondence between the fill and surrounding wood, both as to color and texture, can be closely approximated. Where desired, pigments ogedlyes can be added to get any exact shade de- 8 The second field of usage for which the inven-. tion seems admirably adapted is that of making ornamental inlays in furniture and the like. For

these purposes either organic or inorganic pigments may be incorporated in the plastic to make it any color or texture'desired. The inlay may then be finished with the rest of the article. Obviously, this method of making inlays in wood is far simpler, cheaper and more adaptable than that now in use which consists in fitting and gining minute panels into place in crevices or apertures in the wood. I

The third field of usage for which thisinvention is adapted is that oi attaching metal articles to wood. For instance, where it is desired to secure an absolutely firm, vibrationless connection between a metal member-and a piece of wood, the wood may be apertured, the fill placed in the aperture under pressure. then the metal part inserted while the filler is still plastic. In this way the metal part and the wood become virtually an integral structure.

Having described my invention, I desire to be limited only by the following claims:

1. a material adapted to provide fills or man i aosmss g in wood, said material, comprising, a vinyl resin, ester gum, a volatile solvent for the vinyl resin and ester gum, and a cellniosic material, said components proportioned to provide a very viscous but still tacky plastic material.

2. A material adapted to provide fills or inlays in wood, said material, comprising, a vinyl resin, ester gum, a volatile solvent for the vinyl resin and ester gum, and wood flour, said components proportioned to-provide a very viscous but still tacky plastic material.

3. A material adapted to provide fills or inlays in wood, said material, comprising, a vinyl resin, ester gum, a volatile solvent for the vinyl resin and ester gum,- and substantially one-hundred mesh wood flour, said components proportioned to provide a very viscous but still tacky plastic material.

CLYDE A. CROWLEY. 

